gerich-home/it-depends

var expect = require('chai').expect;
var itDepends = require('../out/build/it-depends.js');

describe('computed with single value dependency', function () {
    var calls;
    var observableValue;
    var computedValue;

    beforeEach(function(){
        var counter = { count: 0 };
        calls = counter;
        
        observableValue = itDepends.value('Bob');

        computedValue = itDepends.computed(function(){
            counter.count++;
            return 'Hello, ' + observableValue();
        });
    });

    it('should not calculate when created', function () {
        expect(calls.count).to.equal(0);
    });

    it('should calculate when requested', function () {
        var actualValue = computedValue();
        expect(actualValue).to.equal('Hello, Bob');
        expect(calls.count).to.equal(1);
    });

    context('after was calculated once', function () {
        beforeEach(function(){
            computedValue();
        });

        it('should not calculate second time if value dependency was not changed', function () {
            var actualValue = computedValue();
            expect(actualValue).to.equal('Hello, Bob');
            expect(calls.count).to.equal(1);
        });
        
        context('after value dependency was changed', function () {
            beforeEach(function(){
                observableValue.write('Jack');
            });

            it('should not recalculate immediately', function () {
                expect(calls.count).to.equal(1);
            });

            it('should recalculate when requested', function () {
                var actualValue = computedValue();
                expect(actualValue).to.equal('Hello, Jack');
                expect(calls.count).to.equal(2);
            });

            context('after value dependency was changed back immediatelly', function () {
                beforeEach(function(){
                    observableValue.write('Bob');
                });

                it('should not recalculate when requested', function () {
                    var actualValue = computedValue();
                    expect(actualValue).to.equal('Hello, Bob');
                    expect(calls.count).to.equal(1);
                });
            });
        });
    });

    context('after value dependency was changed', function () {
        beforeEach(function(){
            observableValue.write('Jack');
        });

        it('should not recalculate immediately', function () {
            expect(calls.count).to.equal(0);
        });

        it('should recalculate when requested', function () {
            var actualValue = computedValue();
            expect(actualValue).to.equal('Hello, Jack');
            expect(calls.count).to.equal(1);
        });
        
        context('after was recalculated', function () {
            beforeEach(function(){
                computedValue();
            });

            it('should not calculate second time if value dependency was not changed', function () {
                var actualValue = computedValue();
                expect(actualValue).to.equal('Hello, Jack');
                expect(calls.count).to.equal(1);
            });
            
        });
        
    });

});